Generally, an attic space can be defined as the space between a horizontal ceiling base and a roof deck above the ceiling base which angles or slopes and rises to a peak. Disposed laterally of the peak is an eaves region of the attic space, which is more generally a triangular section of the attic space proximate the eaves corner or intersection of the roof deck and the ceiling base. In order to provide fire protection for these lateral eaves regions of the attic space, it is known to use automatic fire protection sprinklers positioned medially between the intersection of the roof deck and ceiling base and the peak. In the fire protection industry standard, National Fire Protection Association NFPA 13: Standard for the Installation of Sprinkler Systems (2013 ed.), “automatic sprinklers” are defined as “a fire suppression or control device that operates automatically when its heat-activated element, such as for example, a bulb or soldered link and lever trigger assembly, is heated to its thermal rating or above, allowing water to discharge over a specified area.” Accordingly for these known systems, the functions of fire detection and distribution of the firefighting fluid are physically located at the same site as the automatic sprinkler.
Installation of automatic sprinklers for protecting the eaves regions can present installation constraints or problems because the automatic sprinkler must be installed sufficiently close to the eaves region to thermally respond to a fire therein, yet be sufficiently spaced proximate the eaves region to effectively distribute the firefighting fluid for addressing the fire. Under the fire protection industry standard, National Fire Protection Association NFPA 13: Standard for the Installation of Sprinkler Systems (2013 ed.), criteria is specified for the installation of fire protection sprinkler systems for attic spaces. The installation criteria can include sprinkler spacing and location requirements and application density requirements for sprinklers in order to protect attic spaces with peaked or sloped roofs including protection of the eaves region, the eaves corner and the areas along the base.
FIG. 8.6.4.1.4 of Section 8.6.4.1.3 of NFPA 13 schematically shows sprinklers below a roof deck in an attic space. For the purpose of fire protection of the eaves regions, the protected eaves region is defined by the intersection of the roof and ceiling joists and the distance to the first sprinkler disposed medially of the intersection. The location of this first medial sprinkler relative to the intersection defines a vertical distance to the ceiling deck and a horizontal distance to the intersection along the ceiling deck. Section 8.6.4.1.4.3 of NFPA 13 specifies, for a roof slope of 4 in 12 or greater, a minimum distance in the direction of slope to the intersection for locating the medially disposed automatic sprinkler in order for the sprinkler to properly operate for eaves protection in the attic space. According to Section 8.6.4.1.4.3, the first medial automatic sprinkler is not to be less than five feet (5 ft.) from the intersection of the roof and ceiling joists in the direction of slope. The installation requirements can require that automatic sprinklers be installed and spaced in order to provide, for example, a 0.1 gallon per minute per square foot (0.1 gpm/sq. ft.) fluid distribution density requirement. Accordingly, for known systems using automatic sprinklers, it is believed that the installed vertical distance of the automatic sprinkler to the ceiling base is a function of the 0.1 gpm/sq. ft. density requirement and the five foot (5 ft.) minimum distance in the direction of roof slope.
For known attic fire protection systems, the vertical distance of the sprinkler to the ceiling base presents a limit or design constraint in order to meet the operative and installation requirements of current systems using automatic sprinklers. The vertical limitation on installing automatic sprinklers for protection of the eaves regions can be problematic because it may require installing sprinklers in low clearance areas below the roof or areas with unforeseen obstructions which can make system installation difficult due to the limited heights and areas in which people can operate or fire protection or other equipment can be installed. For example, it is believed that, in order to meet the 5 ft. minimum distance and the 0.1 gpm/sq. ft. density requirements, a medially disposed automatic sprinkler in known systems for eaves protection is to be located at a maximum vertical distance from the ceiling deck ranging from about 29 inches to less than two feet down to about 19 inches. Moreover, the low clearance areas and/or obstructions therein can define unexpected fire growth patterns to complicate the limited thermal responsiveness and fluid distribution patterns of automatic sprinklers. Thus, for current systems using automatic sprinklers in which the thermal response and fluid distribution functions of the system are coupled at the location of the sprinkler, the region or range of eaves protection is constrained by the vertical distance of automatic sprinklers to the ceiling base.